It may be that Festival is dying because it is getting characters that
is doesn't expect. Can you try logging in using the en_US locale and
repeating the test? You should hopefully be able to select the locale
via some sort of "Options" menu on the login screen.
In addition, if you can type 'script' before running the test, and then
Ctrl-D when you done, you can get a typescript of the test. That might
contain useful information.